Performance criteria-aspects of scheduling , Mechanical Engineering

Performance Criteria

This is assumed that an FMS is the part of a superior production process. Consequently the performance of the FMS is not a major goal but imply to attain cost-efficient timely production in the whole system. In hierarchical decentralized systems, the recent state of technology, complex production systems should be controlled. The decisions in the subsystems should be based upon local due dates and local earliest possible beginning times that are offered via the higher-level scheduling system. For a smooth operation of the whole system, a narrow distribution of the deviations from planned process is necessary.

Thus, the usual performance criterion is considered as minimal tardiness. Earliness is neither honored nor punished, since in a complex system the advantages of local earliness are doubtful. The tardiness of all jobs that are ended on time or earlier is zero. Throughput time or machine consumption are not utilized as criteria, since on the long run (we utilize extremely long horizons for the evaluation) the task of a production system is to generate the goods to be delivered on the right time where the demanded throughput times may vary extremely among the jobs; hence, the average throughput time might be a misleading indicator. Obviously, tardiness must all time be looks relative to a specific demanded flow factor distribution, indicated via the time pressure level in the present case.

There are a number of various reasonable measures of tardiness. This is identified that these dissimilar measures in usual cannot be minimized concurrently. In cases of high loads of the system, algorithms which prefer shorter operations offer good values of average tardiness Tmean but at the expense of a minute fraction of the jobs that suffer from extremely large delays. If an FMS is integrated in a superior overall production process, not only a minute value of Tmean is desired but also a narrow distribution of the delays approximately this value, since larger discrepancies among planned and attained completion times create problems for the another local schedule. Thus, the subsequent three criteria are utilized:

Average overall tardiness (over all jobs)

 

 

 

                           581_Performance Criteria-aspects of scheduling.png

Notice that Tmean  is not subtracted in the definition of Trms, consequently Trms  is not a variance but a measure of concerns tardiness and the dissimilarity of Tmean  and Trms  implies the width of the distribution. The associate emphasis is specified to any of the three criteria depends upon the exact situation. Generally, Trms will be the most suitable single criterion.

Posted Date: 3/5/2013 7:25:19 AM | Location : United States







Related Discussions:- Performance criteria-aspects of scheduling , Assignment Help, Ask Question on Performance criteria-aspects of scheduling , Get Answer, Expert's Help, Performance criteria-aspects of scheduling Discussions

Write discussion on Performance criteria-aspects of scheduling
Your posts are moderated
Related Questions
Edge joints: The flanged edge joint is suit- able for plate 1/4 inch or less in thickness and can only sustain light loads. Edge preparation for this joint may be done.

Read two documents that will provide and answer the following questions: 1) You will note from reading the above referenced specifications that fewer valve types are recommended fo

Derive the shape functions N1...N10 for a 10 node triangular element in terms of area coordinates L 1 , L 2 , L 3 .  Nodes are equally spaced on the edges and node 10 is at the cen

which are the different types of molding sands?explain each

Explain the Construction of dc machine The constructional features of a dc machine are given below. A dc machine has two major parts, magnetic ?eld system and armature. The ?eld

alternative theorems for lamis theorem

state the purpose and function of work holder

Q. What is Carbon steel? Carbon steel has long been used for handling concentrated sulphuric acid under ambient temperature and low velocity conditions. In service, a soft sul

Safety Benefits - Industrial Safety An industry or a company which follows safety programmes is benefitted in several ways. The benefits are shared among employer and employee

Q. Handling tools and equipment for skid? Lifting or pulling and provisions for transportation of skid shall be in accordance with GS-904-0103, other relevant parts of contract